PD-L1 mediated the differentiation of tumor-infiltrating CD19(+) B lymphocytes and T cells in Invasive breast cancer.

ABSTRACTAccumulating evidence suggests that B cells play important roles in inhibiting the immune response in autoimmune disorders and human tumors as well as murine tumor models. In an effort to explore the role of B cells in human breast cancer etiology, we examined the presence of CD19+ B lymphocytes in 134 cases of invasive breast carcinoma (IBCa) and 31 breast fibroadenoma, and assessed its relationship with PD-L1 (programmed death-ligand 1) expression in breast cancer. We found that the density of CD19+ B lymphocytes was higher in IBCa compared with fibroadenoma, and significantly associated with increasing tumor grade, negative estrogen status. Similar findings were observed for the expression of IL-10 in IBCa. Meanwhile, CD19+ B lymphocytes were shown to be highly coincident with PD-L1 and IL-10 in IBCa. We further demonstrated that CD19+ B cells can differentiate into CD19+CD24+CD38+ B cells when co-cultured with PD-L1hi MDA-MB231 cells. In addition, the percentage of CD19+CD24+CD38+ B cells was ...